Question

can someone pls send the answer for these​

Answer 1

Step-by-step explanation:

3) (3x-2y)^3= (3x)^3+(2y)^3-3*3x*2y(3x-2y)

=(5)^3=27x^3+8y^3+18*6(5)

=125= 27^3+8y^3+540

= 27^3+8y^3= 125+540

= 27^3+8y^3= 665

4) (a+3b) = 6 [ cubing on both sides ]

(a+3b)^3= 6^3

a^3+(3b)^3+3*a*3b(a+3b)= 216

= a^3+27b^3+9ab(6)= 216

= a^3+27b^3+54ab= 216

Hence proved...

5) a+2b+3c=0

a+2b= -3c. [ cubing on both sides ]

(a+2b)^3= (-3c)^3

a^3+8b^3+3*a*2b(a+2b)= -27c^3

a^3+8b^3+6ab(-3c)= -27c^3

a^3+8b^3-18abc= -27c^3

a^3+8b^3+27c^3= 18abc

Hence proved...

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Answer 2

Answer:

(a - b)3 = a3 - 3a2b + 3ab2 - b3

or

(a - b)3 = a3 - b3 - 3ab(a - b)